Many therapies for lysosomal storage disorders rely on cross-correction of lysosomal enzymes. In globoid cell leukodystrophy (GLD), mutations in GALC cause psychosine accumulation, inducing demyelination, a neuroinflammatory "globoid" reaction and neurodegeneration. The efficiency of GALC cross-correction in&nbsp;vivo, the role of the GALC substrate galactosylceramide, and the origin of psychosine are poorly understood. Using a novel GLD model, we show that cross-correction does not occur efficiently in&nbsp;vivo and that Galc-deficient Schwann cells autonomously produce psychosine. Furthermore, macrophages require GALC to degrade myelin, as Galc-deficient macrophages are transformed into globoid cells by exposure to galactosylceramide and produce a more severe GLD phenotype. Finally, hematopoietic stem cell transplantation in patients reduces globoid cells in nerves, suggesting that the phagocytic response of healthy macrophages, rather than cross-correction, contributes to the therapeutic effect. Thus, GLD may be caused by at least two mechanisms psychosine-induced demyelination and secondary neuroinflammation from galactosylceramide storage in macrophages. GGGGCC hexanucleotide repeat expansions (HREs) in C9orf72 cause amyotrophic lateral sclerosis (ALS)&nbsp;and frontotemporal dementia (FTD) and lead to the production of aggregating dipeptide repeat proteins (DPRs) via repeat associated non-AUG (RAN) translation. Here, we show the similar intronic GGCCTG HREs that causes spinocerebellar ataxia type 36 (SCA36) is also translated into DPRs, including poly(GP) and poly(PR). We demonstrate that poly(GP) is more abundant in SCA36 compared to c9ALS/FTD patient tissue due to canonical AUG-mediated translation from intron-retained GGCCTG repeat RNAs. However, the frequency of the antisense RAN translation product poly(PR) is comparable between c9ALS/FTD and SCA36 patient samples. Interestingly, in SCA36 patient tissue, poly(GP) exists as a soluble&nbsp;species, and no TDP-43 pathology is present. We show that aggregate-prone chimeric DPR (cDPR) species underlie the divergent DPR pathology between c9ALS/FTD and SCA36. These findings reveal key differences in translation, solubility, and protein aggregation of DPRs between c9ALS/FTD and SCA36. Nonalcoholic steatohepatitis (NASH) is becoming one of the leading causes of hepatocellular carcinoma (HCC). Sorafenib is the only first-line therapy for advanced HCC despite its serious adverse effects. Here, we report that at an equivalent of approximately one-tenth the clinical dose for HCC, sorafenib treatment effectively prevents the progression of NASH in both mice and monkeys without any observed significant adverse events. Mechanistically, sorafenib's benefit in NASH is independent of its canonical kinase targets in HCC, but involves the induction of mild mitochondrial uncoupling and subsequent activation of AMP-activated protein kinase (AMPK). Collectively, our findings demonstrate a previously unappreciated therapeutic effect and signaling mechanism of low-dose sorafenib treatment in NASH. We envision that this new therapeutic strategy for NASH has the potential to translate into a beneficial anti-NASH therapy with fewer adverse events than is observed in the drug's current use in HCC. It is unclear whether ex&nbsp;vivo bona fide distinct types of lymphocytes require the availability of different&nbsp;nutrients in the extracellular environment to support cell growth upon activation. Weisel et&nbsp;al. (2020) recently identified fatty acids as a predominant energy source for ex&nbsp;vivo bona fide germinal center B cell growth. Cells within the islet of Langerhans are heterogeneous. Camunas-Soler et&nbsp;al. (2020) implement a patch-seq technique to collect both transcriptomic and electrophysiological data from the same cell. https://www.selleckchem.com/products/ly2880070.html By doing so, they discover new genes that correlate with functional heterogeneity and find that shifts in these correlations indicate β cell compensation in type 2 diabetes. In this issue of Cell Metabolism, Herkenne et&nbsp;al. (2020) show that the mitochondrial fusion protein OPA1 promotes angiogenesis independent of its function in mitochondrial dynamics, identifying a key new therapeutic target to prevent vascular growth during development and tumor formation. In this issue of Structure, Rozbesky et&nbsp;al. (2020) report evidence for direct molecular interactions between Drosophila OTK with Sema1a and glycosaminoglycans, providing insights for OTK's mode of action in axon guidance and possibly in Wnt signaling. In this issue of Structure, Lu et&nbsp;al. (2020) describe an NMR-based study showing the proteasome ubiquitin receptor hRpn13 bound to an extended conformation of K48-diubiquitin that is different from previously described structures of K48-diubiquitin. Observed dynamic binding properties suggest an ability of substrates to hop between proteasome ubiquitin receptors. Neurons and oligodendrocytes communicate to regulate oligodendrocyte development and ensure appropriate axonal myelination. Here, we show that Glycerophosphodiester phosphodiesterase 2 (GDE2) signaling underlies a neuronal pathway that promotes oligodendrocyte maturation through the release of soluble neuronally derived factors. Mice lacking global or neuronal GDE2 expression have reduced mature oligodendrocytes and myelin proteins but retain normal numbers of oligodendrocyte precursor cells (OPCs). Wild-type (WT) OPCs cultured in conditioned medium (CM) from Gde2-null (Gde2KO) neurons exhibit delayed maturation, recapitulating in&nbsp;vivo phenotypes. Gde2KO neurons show robust reduction in canonical Wnt signaling, and genetic activation of Wnt signaling in Gde2KO neurons rescues in&nbsp;vivo and in&nbsp;vitro oligodendrocyte maturation. Phosphacan, a known stimulant of oligodendrocyte maturation, is reduced in CM from Gde2KO neurons but is restored when Wnt signaling is activated. These studies identify GDE2 control of Wnt signaling as a neuronal pathway that signals to oligodendroglia to promote oligodendrocyte maturation. The eight metabotropic glutamate receptors (mGluRs) serve critical modulatory roles throughout the nervous system. The molecular diversity of mGluRs is thought to be further expanded by the formation of heterodimers, but the co-expression of mGluR subtypes at the cellular level and the relative propensities of heterodimer formation are not well known. Here, we analyze single-cell RNA sequencing data and find that cortical pyramidal cells express multiple mGluR subtypes with distinct profiles for different receptor combinations. We then develop quantitative, fluorescence-based assays to define the relative homo- and heterodimer propensities across group-I, -II, and -III mGluRs. We find a strong preference for heterodimerization in a number of cases, including mGluR2 with mGluR3, which we confirm in frontal cortex using in situ RNA hybridization and co-immunoprecipitation. Together, our findings support the biological relevance of mGluR heterodimerization and highlight the complex landscape of mGluR populations in the brain.